1. Field of the Invention
The present invention relates to a parking apparatus for an automatic transmission, and more particularly, to a parking apparatus for an automatic transmission for the installation structure of a sprag shaft and a sprag return spring.
2. Description of Related Art
In general, automatic transmissions are equipped with a parking apparatus that keeps a vehicle stopped by locking a parking gear on an output shaft in a P-range (parking range) with a sprag.
In the parking apparatus, a parking rod operates the sprag when a select lever is moved to the P-range, and the sprag is inserted in a concave-convexo portion on the outer circumferential of the parking gear, thereby locking the parking apparatus.
That is, as shown in FIGS. 1 to 3, as the select lever (not shown) in a vehicle is moved to the P-range, a control lever 1, a select shaft 2, and a detent lever 3 integrally rotate in the direction of an arrow R1 and push a parking rod 4 in the direction of an arrow M1, such that the end of parking rod 4 comes in contact with a sprag 5.
One end of sprag 5 is rotatably fitted on a sprag shaft 6, such that as parking rod 4 comes in contact with sprag 5, sprag 5 rotates (clockwise in the figures) about sprag shaft 6, and accordingly, a sprag protrusion 5a of sprag 5 is inserted in a gear groove of a parking gear 7, thereby locking the parking apparatus.
A sprag return spring 8 is wound on sprag shaft 6, in which one end of sprag return spring 8 is supported by sprag 5 and the other end is supported by a transmission housing 9, such that sprag return spring 8 provides elastic return force to sprag 5, when sprag 5 rotates.
In the parking apparatus having the configuration described above, one end of sprag shaft 6 is inserted in a shaft groove 9a at transmission housing 9 and the other end is in contact with a housing protrusion 11a at a converter housing 11, such that sprag shaft 6 does not axially come out.
That is, housing protrusion 11a of converter housing 11 is in contact with the other end of sprag shaft 6 when transmission housing 9 and converter housing 11 are combined, such that sprag shaft 6 does not axially come out.
However, in the structure of the related art in which sprag shaft 6 is mounted held by housing protrusion 11a of converter housing 11, it is very inconvenient and difficult to form housing protrusion 11a on converter housing 11 and adjust the length of housing protrusion 11a to fit to the length of sprag shaft 6, such that convenience of work decreases and a large amount of working time is needed, and thus, productivity decreases.
In particular, when the position or the depth of shaft groove 9a of transmission housing 9 changes in accordance with the types of transmissions, the position and length of housing protrusion 11a should be correspondingly changed. In this case, it is difficult to freely design, because it needs to consider the problem in ensuring a space for forming housing protrusion 11a and the problem of interference with other parts should be considered.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.